RESUMO
OBJECTIVE: To characterize the clinical phenotype, genetic origin, and muscle pathology of patients with the FKRP c.1387A>G mutation. METHODS: Standardized clinical data were collected for all patients known to the authors with c.1387A>G mutations in FKRP. Muscle biopsies were reviewed and used for histopathology, immunostaining, Western blotting, and DNA extraction. Genetic analysis was performed on extracted DNA. RESULTS: We report the clinical phenotypes of 6 patients homozygous for the c.1387A>G mutation in FKRP. Onset of symptoms was <2 years, and 5 of the 6 patients never learned to walk. Brain MRIs were normal. Cognition was normal to mildly impaired. Microarray analysis of 5 homozygous FKRP c.1387A>G patients revealed a 500-kb region of shared homozygosity at 19q13.32, including FKRP. All 4 muscle biopsies available for review showed end-stage dystrophic pathology, near absence of glycosylated α-dystroglycan (α-DG) by immunofluorescence, and reduced molecular weight of α-DG compared with controls and patients with homozygous FKRP c.826C>A limb-girdle muscular dystrophy. CONCLUSIONS: The clinical features and muscle pathology in these newly reported patients homozygous for FKRP c.1387A>G confirm that this mutation causes congenital muscular dystrophy. The clinical severity might be explained by the greater reduction in α-DG glycosylation compared with that seen with the c.826C>A mutation. The shared region of homozygosity at 19q13.32 indicates that FKRP c.1387A>G is a founder mutation with an estimated age of 60 generations (â¼1,200-1,500 years).
RESUMO
Abstract Isolated sulfite oxidase deficiency (ISOD) is a devastating, neurometabolic disorder caused by mutations in the SUOX gene necessary for the final step in the sulfur-containing amino acid catabolic pathway. Patients classically present in the neonatal period with neurologic manifestations. Biochemical findings include elevated sulfocysteine, low cystine and undetectable homocysteine with normal uric acid levels. Other associated biochemical markers include elevated plasma alpha-aminoadipic semialdehyde and piperideine-6-carboxylic acid. We report a patient with classic neonatal onset ISOD (refractory seizures, hypertonicity, brain abnormalities, pathogenic SUOX mutations). Her clinical course was marked by extreme irritability, prompting the use of a low methionine and cystine diet to decrease toxic metabolites thought to be contributing to her symptoms. Biochemical markers and extreme irritability improved with dietary treatment (methionine=30mg/kg/day). She died of sepsis in early infancy, precluding long term follow-up. This case reviews the potential benefits and limitations of diet therapy in this rare disorder.